This invention relates to a solvent composition. In a more particular aspect, this invention concerns itself with a solvent mixture that is particularly adapted for use in dissolving and removing epoxy resinous formulations such as epoxy rigid foams, paints and cured resins.
The epoxy resins constitute a rather large class of thermosetting, polyether, resinous intermediates which are generally formed through a polymerization reaction between bisphenol and epichlorohydrin. The uncured intermediate is of no particular value until it is reacted or hardened through the use of a variety of hardening of curing agents. When cured or hardened, the resinous material finds wide application for use as coatings, adhesives, castings and foams. Laminates of epoxy resins and glass cloth have been utilized in the repair of damaged automobile and small boat hulls. One of their more important modern day uses resides in their application as a foam encapsulant for electronic components and circuit boards. Unfortunately, the inherent solvent resistance of epoxy resins presents certain problems. Great difficulty is encountered in removing the protective encapsulant from the electronic component in order to effect repair or replacement of any of the individual units making up the electronic component or the electronic circuit board. Heretofore, it was necessary to grind or burn the foam encapsulant or, in the alternative, rely on a number of corrosives solvents which utilized strong acid or basic catalysts as the primary component of the solvent mixture. Oftentimes, the use of grinding techniques or strong solvents resulted in excessive physical damage to the electronic component. In addition, corrosion often occurred resulting in even greater damage. As a result, the repair or replacement of component parts could not be undertaken and the components had to be discarded at a large economic loss.
In order to avoid economic loss, hazardous health conditions from the corrosive solvent vapors, health hazards from the pyrolisis of the coatings and, most importantly, facilitate the repair and maintenance of electronic components, it was found necessary to develop a novel solvent mixture that would be effective in dissolving and removing epoxy resins whether in the form of a thick coating, paint-like coating, foam encapsulant or foamed structure.
As a result of the research effort generated for the purpose of providing for the effective removal of epoxy resins, it was found that a mixture containing dichloromethane, methanol and distilled water provided a solvent that overcame the problems associated with prior art methods utilized in the removing and dissolving of epoxy resins.